About the Author: (from The American Mathematical Monthly, vol. 80, (1973)) Martin D. Davis received his Princeton Ph.D. under Alonzo Church. He has held positions at University of Illinois, IAS, University of Calif.-Davis, Ohio State University, Rensselaer Poly, Yeshiva University and New York University, and he spent a leave at Westfield College, London. He has done research in various aspects of the foundations of mathematics, and is the author of Computability and Unsolvability (Gordon and Breach, 1967), and First Course in Functional Analysis (Gordon and Breach, 1967).